Abstract:

The origin, development and the ultrastructure of secretory cavities in leaf of Ginkgo biloba and its relation to the secretory products were studied under light and electron microscopes. The results indicated that the formation pattern of the secretory cavities was schizo lysigeneous. First, some original secretory cells in the center of secretory cavities began to expand and dissolved, and small spaces appeared between the cells. Then more secretory cells dissolved and made the space larger, meanwhile the former secretory cells in the center degenerated, autolyzed and sloughed off in the cell spaces. The secretory product in the secretory cavities of G. biloba was mainly synthesized in ER and plastids. More or less, mitochondria, Golgi body and ground cytoplasm also took part in the synthesis and transportation of secretory products. After synthesized in ER and plastids, the secretory products approached the plasmalemma and fused their membranes with the latter in the form of small vesicles, and then was eliminated to the spaces between the plasmalemma and the wall. At last the secretory products percolated through the wall that faded into an even looser mesh of fibrillar material toward the cavity.

Key words: Ginkgo biloba, Secretory cavity, Ultrastructure, Secretory product